KR100493668B1 - Method for searching channel automatically in digital television - Google Patents

Abstract

In the channel search method when the digital cable is in the QAM mode, when the automatic channel search command is received from the user, the channel number is determined and set to the first QAM mode, and whether a signal exists in the channel. If it is determined whether a signal exists in the corresponding channel as a result of the determination, it is determined whether the timing recovery corresponds to the first QAM timing recovery with respect to the signal. If it does not correspond to the timing recovery, set to the second QAM mode for the channel, determine whether the timing recovery corresponds to a second predetermined QAM timing recovery for the signal set to the second QAM mode, As a result of the determination, the timing recovery is predetermined for the signal set to the second QAM mode; If it corresponds to AM timing recovery, it is determined whether an error has occurred with respect to the corresponding signal, and if the error does not occur with the signal, the corresponding channel is determined to be normal, and the decoding waiting time of the decoder chip is shortened. This minimizes the time users wait for meaninglessness.

Description

Method for searching channel automatically in digital television}

The present invention relates to a digital TV automatic channel search method that can reduce the time required for automatic channel search in the digital TV.

In line with the recent digital trend, standardization of digital broadcasting is in full swing in the field of TV broadcasting. When you purchase a digital TV and install it for the first time or relocate, you can save the channel information about the valid channels that can be received from the digital TV in the internal memory. -channel scan), by storing the scanned channel information in the internal memory of the digital TV, the information is referred to during the channel-related operation of the digital TV.

In general, the expected number of channels of digital television is tens of times that of analog television. Therefore, in digital broadcasting, the provision of tens to hundreds of channels increases the viewer's choice and makes the program selection more complicated.

For this reason, a user often registers a desired predetermined channel among the channels of the digital broadcast by referring to additional information of each channel received from the outside and uses only the registered channel.

In other words, users can use the automatic channel search function to identify the channels that are available for viewing during the first purchase or use of the digital TV.

In the case of channel tuning in a digital TV, a decoder capable of decoding a digital signal receives an input signal and determines whether the corresponding channel is a channel in which the digital signal is normally received through various decoding processes.

That is, the decoder determines whether a signal exists for each channel, and if there is a signal of the corresponding channel, determines whether the channel is normal. That is, the decoder determines whether the corresponding signal is a normal signal through the decoding process until the input signal has no digital signal, analog signal, meaningless signal, or no signal at all.

The method of automatic channel search in digital TV is to set the decoder according to VSB and QAM, and then decode in the chip to check whether the last step, the Forward Error Check (FEC) lock, is normal to the corresponding channel. Determine whether there is.

In this case, even the channel without the signal itself goes through the same process, so that 250ms for VSB and 700ms for QAM should be waited for checking the final stage of signal decoding.

In the case of the cable having 135 channels, it takes more than 3 minutes when the automatic channel search is performed with the current structure, so the user has to wait for the digital TV search for the time.

A conventional method for checking whether a signal is normal for each channel for automatic channel search will be described with reference to FIGS. 1 and 2.

1 is a flowchart illustrating a channel checking method when a conventional digital cable is in a QAM mode.

Referring to FIG. 1, when the digital TV receives an automatic channel selection command from the user (S100), the digital TV determines the number of the corresponding channel (S102).

After performing step 102, the digital TV sets the 64QAM mode for the channel (S104). If a predetermined time elapses, it is determined whether an error occurs (S106). The method of determining whether an error occurs uses a Forward Error Check (FEC) method. Here, in many cases, the FEC lock is often faster, but the delay is 200ms or more in case the FEC lock is delayed depending on the signal.

If an error occurs as a result of the determination in step 106, the digital TV sets the 256QAM mode for the channel (S108).

Then, when the predetermined predetermined time elapses, the digital TV determines whether an error occurs (S110).

If an error occurs as a result of the determination of step 110, the digital TV determines that the input signal is abnormal and determines that there is no channel (S112).

If no error occurs as a result of the determination of step 106, the digital TV determines that the corresponding channel is normal (S114).

If no error occurs as a result of the determination of step 110, the digital TV determines that the corresponding channel is normal (S114).

2 is a flowchart illustrating a channel checking method when a conventional digital cable is in a VSB mode.

Referring to FIG. 2, when an automatic channel search command is received from the user (S200), the digital TV determines the number of the corresponding channel (S202).

Then, the digital TV sets the VSB mode for the channel call (S204). When a predetermined time elapses, the digital TV determines whether an error occurs (S206).

If an error occurs as a result of the determination in step 206, the digital TV determines that the input signal is abnormal and determines that there is no channel (S208).

If no error occurs as a result of the determination of step 206, the digital TV determines that the channel is normal (S210).

However, in the conventional method as described above, even a channel without a signal itself must be determined whether a signal exists, so 250 ms for VSB and 700 ms for QAM must be waited to determine whether the FEC (Forward Error Check) lock is the final step of signal decoding. Therefore, there is a problem that the overall automatic channel search time is long.

Accordingly, an object of the present invention is to provide an automatic channel search method in a digital TV which can shorten the time required for automatic channel search by changing the automatic channel search algorithm of the digital TV.

According to an aspect of the present invention to achieve the above object, in the channel search method when the digital cable is in the QAM mode, when an automatic channel search command is received from the user, by determining the number of the channel to the first QAM mode And determining whether or not a signal exists in the corresponding channel. If the signal is present in the corresponding channel, it is determined whether the timing recovery corresponds to a predetermined first QAM timing recovery. If the recovery does not correspond to the first predetermined QAM timing recovery, set the second QAM mode for the signal, and whether the timing recovery corresponds to the second predetermined QAM timing recovery for the signal set in the second QAM mode. Determine whether the signal is equal to or equal to the signal set in the second QAM mode. If the recovery corresponds to the second predetermined QAM timing recovery, it is determined whether an error occurs with respect to the corresponding signal, and if the error does not occur as a result of the determination, the channel is determined to be normal. A method is provided.

The first QAM mode is 64QAM and the second QAM mode is 256QAM.

The NS flag is used to determine whether a signal exists in the corresponding channel.

If the timing recovery with respect to the signal set in the first QAM mode corresponds to a first predetermined QAM timing recovery, it is determined whether an error occurs for the signal, and if the error occurs for the signal, the channel is absent. Judging by.

If no signal exists in the corresponding channel, it is determined that there is no channel.

According to another aspect of the present invention, in the channel search method when the digital cable is in the VSB mode, when an automatic channel search command is received from the user, the number of the corresponding channel is determined and set to the VSB mode, and a signal is applied to the channel. Determining whether there is a signal, and if a signal exists in a corresponding channel as a result of the determination, determining whether an error occurs. If the error does not occur with the signal as a result of the determination, the corresponding channel is determined to be normal. An automatic channel search method is provided in a digital TV.

If no signal exists in the corresponding channel, it is determined that there is no channel for the corresponding channel, and if an error occurs in the signal, it is determined that there is no channel for the corresponding channel.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram schematically showing the configuration of a digital TV according to an embodiment of the present invention.

Referring to FIG. 3, the digital TV includes an IR receiver 300, a controller 310, a tuner 320, a decoder 330, a video processor 340, an output 350, and a storage 360. .

The IR receiver 300 receives a remote control code selected by a user and transmits the code to the controller 310.

The controller 310 analyzes a remote control code transmitted from the IR receiver 300 and transmits remote control code analysis information to a corresponding device.

For example, if the remote control code interpretation information is a channel confirmation request command, the controller 310 transmits the channel confirmation request command to the decoder 330.

The storage unit 360 includes a flash ROM for storing software such as an operating system and a DRAM for storing a virtual screen in the form of a bitmap that can be represented in a CRT area.

The tuner 320 converts the radio signal transmitted through the antenna into an IF signal according to the analysis information of the remote control code selected by the user and transmits the radio signal to the decoder 330.

The decoder 330 converts the IF signal transmitted from the tuner 320 into TP data and transmits the signal to the video processor 340 during the automatic channel search.

In addition, the decoder 330 determines whether the channel is a normal channel with respect to a channel including the IF signal transmitted from the tuner 320.

That is, the decoder 330 determines that there is no channel by determining a channel having no signal, an analog signal channel, and a channel having no meaning, and determines that the channel including the digital signal is normal.

A detailed description of how the decoder 330 determines whether a channel is normal will be described with reference to FIGS. 4 and 5.

The video processor 340 converts the TP data transmitted from the decoder into image data and transmits the image data to the output unit 350.

The output unit 350 corrects the image data so that the image data transmitted from the video processor 340 is displayed according to the screen.

4 is a flowchart illustrating a channel setting method when the digital cable is in the QAM mode according to an embodiment of the present invention.

Referring to FIG. 4, when an automatic channel search command is received from the user (S400), the digital TV determines the number of the corresponding channel (S402).

Then, the digital TV sets the 64QAM mode for the corresponding channel (S404), and determines whether a signal exists in the corresponding channel using the NS flag (No signal flag) (S406). Here, the signal may be a digital signal. In order to determine whether a signal exists in the channel, the digital TV checks a decoder chip register after 50 ms to determine whether an NS flag is present.

As a result of the determination in step 406, if a signal exists in the corresponding channel, the digital TV determines whether the timing recovery of the signal corresponds to a predetermined 64QAM timing recovery (S408).

If the timing recovery of the signal corresponds to a predetermined 64QAM timing recovery, the digital TV determines whether an error has occurred in the signal (S410).

If an error occurs in the signal as a result of the determination in step 410, the digital TV determines that there is no channel for the corresponding channel (S412).

If the signal does not generate an error as a result of the determination of step 410, the digital TV determines that the corresponding channel is normal (S418).

If there is no signal in the corresponding channel as a result of the determination of step 406, the digital TV determines that there is no channel (S412).

If the timing recovery does not correspond to 64QAM timing recovery, the digital TV sets the 256QAM mode with respect to the input signal (S414).

After performing step 414, the digital TV determines whether the timing recovery corresponds to a predefined 256QAM timing recovery (S416).

As a result of the determination of step 416, if the timing recovery for the signal corresponds to a predefined 256QAM timing recovery, the digital TV performs step 410.

If it is determined in step 416 that the timing recovery for the signal does not correspond to a predefined 256QAM timing recovery, the digital TV performs step 412.

In the case of QAM, after setting the decoder, the decoder checks the register to confirm the presence or absence of the corresponding channel signal, and if there is no signal, it is determined that there is no channel without checking the mode switching and error occurrence, and then confirming the next channel. This can save time when there is no signal.

The time for setting information about the channel in the signal presence check register is 100 ms or less.

5 is a flowchart illustrating a channel checking method when a digital cable is in a VSB mode according to an embodiment of the present invention.

Referring to FIG. 5, when an automatic channel search command is received from the user (S500), the digital TV determines the number of the corresponding channel (S502).

Then, the digital TV sets the VSB mode for the corresponding channel (S504), and then determines whether a signal exists in the corresponding channel (S506).

As a result of the determination in step 506, if a signal exists in the corresponding channel, the digital TV determines whether an error occurs in the signal (S508).

If an error occurs in the signal as a result of the determination in step 508, the digital TV determines that there is no channel (S510).

If no error occurs in the signal as a result of the determination of step 508, the digital TV determines that the corresponding channel is normal (S512).

If there is no signal in the channel as a result of the determination in step 506, the digital TV determines that there is no channel (S510).

In the case of VSB, after setting the decoder, the decoder checks the register that can confirm the existence of the corresponding channel signal, and if there is no signal, it does not check whether an error occurs. This saves time if there is no signal.

The time for setting information about a channel in the signal presence check register may be 10 ms or less.

If there is a signal after checking whether there is a signal, check whether there is an error and determine whether it is a normal channel.

The present invention is not limited to the above embodiments, and many variations are possible by those skilled in the art within the spirit of the present invention.

As described above, according to the present invention, in the case of the digital cable, after setting the decoder, the chip checks the register for confirming the existence of the corresponding channel signal, and if there is no signal, it is determined that there is no channel without mode switching and error checking. As the next channel can be checked, the digital TV can provide an automatic channel search method that can reduce the time when there is no signal.

In addition, according to the present invention, if a signal is present after checking whether a signal exists, a mode recovery is performed by checking timing recovery, so that an automatic channel search method can be provided in a digital TV that can shorten time.

In addition, according to the present invention, in the case of VSB, after setting the decoder, the chip checks a register for checking whether a corresponding channel signal exists, and when there is no signal, the next channel can be checked by determining that there is no channel without performing an error check. If not, the digital TV can provide an automatic channel search method that can save time.

In addition, according to the present invention, when applying the algorithm for shortening the time in the automatic TV search in the digital TV, the decoding waiting time of the decoder chip for the channel with no signal, the analog signal channel, and the channel with a meaningless signal is reduced Therefore, it is possible to provide an automatic channel search method in a digital TV that can minimize the user's waiting time without meaning.

1 is a flowchart illustrating a channel checking method when a conventional digital cable is in a QAM mode.

2 is a flowchart illustrating a channel checking method when a conventional digital cable is in VSB mode.

Figure 3 is a block diagram schematically showing the configuration of a digital TV according to an embodiment of the present invention.

4 is a flowchart illustrating a channel setting method when the digital cable is in the QAM mode according to an embodiment of the present invention.

5 is a flowchart illustrating a channel checking method when the digital cable is in the VSB mode according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

300: IR receiver 310: control unit

320: tuner 330: decoder

340: video processor 350: output unit

360: storage

Claims (6)

In the channel search method when the digital cable is in the QAM mode, When the automatic channel search command is received from the user, determining a number of the corresponding channel and setting the channel number to the first QAM mode; Determining whether a signal exists in a corresponding channel; Determining whether a timing recovery corresponds to a first QAM timing recovery with respect to the signal when a signal exists in a corresponding channel as a result of the determination; Setting the second QAM mode for the corresponding channel if the timing recovery does not correspond to the first QAM timing recovery as a result of the determination; Determining whether a timing recovery corresponds to a second predetermined QAM timing recovery with respect to the signal set in the second QAM mode; Determining whether an error occurs with respect to the signal when the timing recovery corresponds to a second predetermined QAM timing recovery for the signal set to the second QAM mode; and If an error does not occur in the signal as a result of the determination, determining the corresponding channel as normal Automatic channel search method in a digital TV comprising a. The method of claim 1, Wherein the first QAM mode is 64QAM and the second QAM mode is 256QAM. The method of claim 1, And determining whether a signal exists in the corresponding channel by using an NS flag. The method of claim 1, Determining whether an error occurs with respect to a signal set in the first QAM mode when a timing recovery corresponds to a predetermined first QAM timing recovery; And determining that there is no channel if an error occurs in the corresponding signal as a result of the determination. The method of claim 1, And determining that there is no channel if the signal is not present in the corresponding channel. In the channel search method when the digital cable is in the VSB mode, If the automatic channel search command is received from the user, determining the number of the corresponding channel and setting the VSB mode; Determining whether a signal exists in a corresponding channel; Determining whether an error occurs when a signal exists in a corresponding channel as a result of the determination; and Determining that the channel is normal if an error does not occur with respect to the signal, Automatic channel search method in a digital TV comprising a.